Dryer for sheet material



June M, 197 A. STOCK DRYER FOR SHEET MATERIAL 6 Sheets-Sheet l Filed July 29, 1964 INVENTOR. AUGUST STOCK ATTORNEYS June 13, I? s'rac 3,324,511

DRYER FOR SHEET MATERIAL Filed July 29, 1964 e sheet -sheet 2 f 22 x I I INVENTOR. ,aususr srpck June 13, 1967 Filed July 29, 1964 A. SBTQCBK DRYER FOR SHEET MATERIAL 6 Sheets-Sheet 5 INVENTOR. A ueus T 3 T0 c/r ATTORNEYS June E, 16"? A. STOCK. 3,324,571

DRYER FOR SHEET MATERIAL Filed July 29, 1964 6 Sheets-Sheet 4.

I INVENTOR, A UGUS T 5 705% June l3, W6"? A. srocx 3 324,,5W

DRYER FOR SHEET MATERIAL Filed July 29, 1964 6 Sheets-Sheet 5 INVENTOR AUGUST STOCK ATTORNEYS June 113, A. STOCK DRYER FOR SHEET MATERIAL 6 Sheets-Sheet 6 Filed July 29, 1964 INVENTOR AUGUST STOCK A TTOR/VEYS 3,324,571 DRYER FOR SHEET MATERIAL August Stock, Alsfeld, Hesse, Germany, assignor to Moore Dry Kiln Company, Jacksonville, Fla, a corporation of Florida Filed July 29, 1964, $67!. No. 385,883 6 (Ilaims. (Cl. 34-160) This invention pertains to sheet material dryers, and particularly to dryers of the jet tube type.

The invention is particularly adapted to the drying of wood veneer.

A general object of the invention is to provide an improved sheet material dryer.

A further object is to provide a wood veneer dryer of improved efficiency and simple construction in which thin veneer sheets or board-like materials may be fed with minimized chance of jamming or damage while passing thru the dryer.

Further objects of the invention are to provide, in a wood veneer dryer, structure which is readily adjustable, easily cleanable, readily controllable to provide adjustable drying effects, and which minimizes the chance of damaging the veneer sheets. Still further objects are to provide, in a dryer, arrangements which minimize power requirements and provide minimum drying time with minimum tendency to damage the material being dried.

The invention also relates to certain improvements in parts and subcombinations embodied in the dryer disclosed herein.

The novel features which are believed to be characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a side elevation partially broken away and in section of what may be termed the back side of a dryer embodying the invention;

FIG. 2 is a similar view showing the front side thereof;

FIG. 3 is an end elevation partially broken away showing the green end of the dryer;

FIG. 4 is a sectional view on an enlarged scale taken along line 4-4 of FIG. 1;

FIG. 5 is a sectional view of a portion of the dryer taken generally along line 5-5 of FIG. 4 and including portions broken away and in section to disclose details of the arrangement;

FIG. 6 is a sectional view similar to FIG. 5 but taken generally along line 6-6 of FIG. 4;

FIG. 7 is a sectional view on a further enlarged scale of jet tube portions of the dryer taken along line 7-7 of FIG. 5;

FIG. 8 is a similar view taken along line 8-8 of FIG. 6 showing details of the rollers, and bearings and drive for the rollers;

FIG. 9 is a sectional view taken along line 99 of FIG. 8 showing details of the bearing and mount for an upper floating roller;

FIG. 10 is a sectional view taken along line 1010 of FIG. 8 but on a still further enlarged scale showing details of the bearing and mount for a lower driven roller;

FIG. 11 is a sectional view of the bearing taken along line 11-11 of FIG. 10, the roller shaft being omitted;

FIG. 12 is a sectional view of the bearing and mount for the lower driven roller taken along line 1212 of FIG. 10, the roller shaft being omitted;

FIG. 13 is a large scale sectional fragmentary view showing details of portions of the jet tubes and including 3,324,571 Patented June 13, 1967 a fragmentary representation of a veneer sheet being dried;

FIGS. 14 and 15 are fragmentary sectional views of portions of a jet tube and representations of veneer being dried illustrating alternative adjusted positions of the jet tube; and

FIG. 16 is a fragmentary view of the slot portion of a jet tube taken generally along line 16-46 of FIG. 13.

A dryer 1 embodying the invention is seen in FIGS 1, 2 and 3 to include a heated green or wet end zone 2 and a heated dry end zone 3, the green end zone comprising two dryer sections 4 and 5 and benig defined zetween a partition 6 and end wall 7. The dry end zone comprises sections 8 and 9 and may also include section 10 and thus be a three section zone. Alternatively, additional sections or zones may be interposed between sections 9 and 10, as indicated by the interruption at 11. While a typical dryer according to the invention may comprise two or three zones each of which comprise two or three sections, it may be appropriate in specific applications to employ single section zones and to provide only one or more than three zones. The final dry end zone may be operated without heat as a cooling zone.

It will be understood that each zone is separated from the next by a partition such as partition 6.

Feeding means 12, such as roller beds 13, are ar ranged at the green end to feed veneer sheets on predetermined levels through suitable openings in the end wall 7 into horizontal paths through the dryer between jet tubes 14 and rollers 15, 16. Chains 17, 18 driven by motors 19, 20 are arranged to drive the driven rollers, including roller 16, and floating rollers, including roller 15, cooperate therewith to advance the veneer sheets or other board-like sheet material through the dryer to the dry or delivery end and out to delivery roller 21.

The dryer comprises an outer housing 22 including front and back walls 23 and 24, respectively, each wall being provided with a pair of doors for each section. Section 5, for example, includes doors 25, 26 supported on hinges such as hinge 27, in the front wall, and doors 28, 29 in the back wall. The doors and walls are preferably heat insulated. The rollers and jet tubes of each section are mounted on upright frame members or stanchions, such as members 30, 31, which are spaced inwardly of the respective side walls of the outer housing. Each section, above a horizontal partition, such as sheet metal partition 32 or partition 33 of section 5 and 4, respectively, comprises a heating space, such as space 34 of section 4, within which is disposed suitable heating means, such as a natural or other gas burner 35, and gaseous medium circulating means, such as fan 36. Each fan is belt driven from a respective motor, such as motor 37 for fan 36 of section 4. When two or more sections comprise a zone, the heating spaces of the sections of the zone are preferably not divided each from the next by a partition 6 but each communicates openly with the adjacent section. For each zone a vent stack, such as stack 38, communicates with the heating space between the fan and the burner for exhausting a portion of the gaseous medium therefrom.

In the operation of the dryer, heated gaseous medium is circulated within housing 22 through the heating space, thence downwardly and into jet tubes from which the medium issues into contact with the sheet material to be dried, and, following such contact, the medium returns to the heating space for reheating and recirculation. The gaseous medium typically comprises primarily moisture ladened air, and it may also include such gases and vapors as may be given off at the elevated temperature from the materials being dried. The gaseous medium may also include combustion products of the heater if a direct flame type heater is employed, such as the heater shown at 35.

FIG. 4 shows the interior arrangement at section 4 of the dryer. The heating space 34 above partition 33 carries the gaseous medium, of which the motion is represented by arrows 39, 40, from fan or blower 36 past heater and thence downwardly into a front or pressure chamber 41 defined between doors 42 and a wall 43. Each of a plurality of jet tubes, including tubes 44 and 45, opens through apertures 46 and 47. Each such aperture is defined by an inturned circular ring or shoulder 48 which extends into and supports the open end 49 of the jet tube. The fit of the ring into the tube is tight enough to hold the tube against rotational or longitudinal movement, except when it may be intentionally rotated or longitudinally withdrawn by substantial manual force. The wall 4-3 comprises a plurality of apertured plate members, including member 50 shown in this view, connected to upright frame members by means of bolts 51 passing through an inturned edge flange portion 52 of plate member 50. At the end of each section, a vertical post member, such as member 53 may be provided to support the outer housing 22.

At the rear or drive side of the dryer, the jet tubes are mounted by means of support rods 54, fixedly secured to the respective jet tubes 44, 45 and extending horizontally and coaxially thereof in a direction rearwardly of the dryer. Each rod extends through a suitable circular opening or socket in a respective short horizontal support member, such as member 56, which extends between and is suitably attached to adjacent upright rear or drive side support members or stanchions, such as member 57. The individual jet tubes may be manually rotatably adjusted into desired position, the rod 54 or 55 rotating in its socket.

The heated gaseous medium entering tubes 44 and 45, as indicated by arrows 58 and 59, respectively, issues from upper tube 44 in a downward direction as shown by arrow 60, through slot 61 and in an upward direction, as shown by arrow 62, through slot 63 of the lower tube 45. The material to be treated passes through the space or path 64 between tubes 44 and 45 thereby to be contacted above and below by the gaseous medium from the jet slots. In the embodiment shown, there are three decks or tiers of tubes providing three horizontal material paths 64, 65 and 66, although more or less than three decks may be employed if desired.

The gaseous medium, having issued from the slots and having contacted the material being treated, flows from the space around the tubes, such as space 67, 68

into a rear or negative pressure chamber 69 at the drive side of the section, and thence, as represented by arrows 70, upwardly and through fan 36 again into the heating chamber 34. The fan is disposed in a suitable opening 71 in partition 72 which separates the collection or negative pressure chamber 69 from the heating chamber 34. A portion of the gaseous medium is exhausted into the atmosphere through stack 38 before reheating thereof. An adjustable directing vane 73 may be provided to permit regulation of the portion of the medium to be exhausted. The vapor and gases given off by the material treated tend to increase the volume of gaseous medium in the housing, and there may, thus, be substantial exhaust through stack 38 without changing the amount of gaseous medium in the housing, and while there may be appreciable leakage of air into the housing around the doors and through the end walls and otherwise, the primary function of the exhaust stack is to remove gases and vapor at approximately the rate at which they are given off by the material being treated. In this manner the quality of the gaseous medium as to its components, and particularly as to humidity or moisture content, is maintained substantially constant. Suitable controls, well known in the art, are preferably provided for adjusting the exhaust rate,

internal pressure, feed rate, fan speed, rate of fuel supply and the like to maintain the desired conditions, and such controls may respond automatically, if desired, to humidity and temperature sensitive control devices. Such controls, being well known, are omitted from the drawings for the sake of clarity.

Drive chains, sprockets, star gears and other elements associated with the roller system are omitted for clarity from FIG. 4.

As seen in FIG. 5, the upright supporting channel members, including member 57, between adjacent ones of which the horizontal support members 56 extend, foot on a rigid foundation, including a sill 74 and concrete pad 75. The full support for the jet tubes at the rearward side of the dryer is provided through the upright members, such as member 57. Each of these upright members is connected, as by a bolt 76 to an upper frame member 77 which extends only for the length of the section and which terminates at upright 78, to which it is joined by a bolt 79 passing through longitudinal slot 80 in member 77. Member 77 may, accordingly, expand and contract longitudinally without causing any movement of member 78, and the horizontal frame member 81 of section 5, which is also attached to member 78 by bolt 79 through a slot in member 81, is similarly unaffected by expansion and contraction of member 77. Throughout the length of the dryer, at least one end of each horizontal frame member is provided with a slip joint or expansion joint connection to the similar frame members of the next occurring sections. While a slot 80 is shown in member 77 at post or support 78, such slot may not be necessary if end wall 22 is permitted to bow slightly inwardly and outwardly with expansion and contraction of member 77, and if a slip joint is arranged at at least one end of member 81. It is to be noted that there is no rigid direct connection between the outer housing and the inner section frame elements which would, due to thermal expansion and contraction, interfere with the alignment of the jet tubes and drive rollers. The tubes and rollers of each section are supported by the uprights, such as member 57, directly from the foundation, and once properly adjusted in height to feed material, such as the veneer sheet 86, in a straight path represented by an arrow at 65 from one end to the other of the dryer, this adjustment is substantially unaffected by temperature changes, except for very small changes in height above the foundation due to change in length of the upright members, which changes take place substantially uniformly and are not objectionable. Twisting effects on the section frames are, accordingly, minimized. Such expansion and contraction of members extending from front to back of each section as may occur result in no appreciable twisting or straining of the roller deck, jet tube and frame construction. Since the outer housing is not rigidly connected to the section frame, the outer housing, which may include large sheets of metal, may twist and buckle from temperature changes without interference with the roll and tube alignment.

The upright frame members, such as upright 57, support not only the adjacent jet tube ends through cross members such as member 56, but also support the weight of driven feed rolls, such as rolls 82 and 83, the weight of driving chains for the driven rolls, including chains 17 and .18, and, since the weight of floating rolls 84 and 85 is supported by the underlying driven rolls, both when a veneer sheet 86 is interposed therebetween and when there happens to be no sheet between the rolls, the uprights also carry the weight of the floating rolls, plus the slight weight of the veneer sheet.

Each driven roll is provided with a chain sprocket 87 cooperative with a drive chain, such as chain 18. A plurality of supports 88, 89 are attached to the frame uprights to support the return flight of each chain, such as flight 90 of chain 17.

Each of the jet tubes has a closed end 91 which may be provided with a cleanout opening closed by a moveable vane or door 92. Since the tube ends opposite those shown in FIG. 5 are open, as seen in FIG. 4, access may be had to the interior from either or both ends of each tube.

Section 4 is seen to be separated from section 5 by a partition 93 which has a slot therethrough at each veneer path, such as slot 94 for path 65, through which the veneer passes from section to section and from zone to zone. Since sections 4 and 5 are included in the same green end zone, partition 93 terminates at horizontal partition 33, and no partition separates heating chamber 34 of section 4 from heating chamber 95 of section 5.

In the view of FIG. 6 it will be seen that each of the cylindrical jet tubes has a slot 61, 63 extending substantially throughout the length of the tube, the .upper tube 44 having its slot 61 directed downwardly and the lower tube 45 having its slot 63 directed upwardly, whereby to expel heated air or gaseous medium toward the upper and lower faces of the sheet material which passes between the tubes.

The lower chain driven roller and the upper floating roller of each pair are interconnected at the front side of the section by intermeshed star gears, including star gear 96 of a lower driven roller and star gear 97 of an upper floating roller of the pair as further illustrated in FIG. 8 as later described.

It will be noted from the geometry disclosed in FIG. 6 that a veneer sheet 86 or 86' travelling in path 65 has little freedom to depart from or miss the path. Thus, if the leading edge 98 of sheet 86' tends to rise or fall, such as may occur from warping, or from tilting of short sheets, or from the effects of unbalanced flow of the jets of gas impinging on the sheet or from any other cause, the displaced or out of line leading edge 98 meets a curved surface which urges the sheet back into the path. The rotating rollers 82 and 85 will receive the leading edge 98 and direct it between the rollers even though the edge meets one or the other of these rollers out of line. The sheet, it will be seen, is prevented from too great depart ure from the path because such departure would result in contact with one or the other jet tubes 99, 100. As the leading edge feed through the rollers 82, 85, it may, upon departure from the path, meet a jet tube 101, or 102, but it will be seen that the curved shape of the jet tubes and the position and arrangement thereof are such as to return a misdirected leading edge back into the path. The edges 103 of slot 94 in partition 93 are inclined in the direction of travel of the sheets and have a similar directive effect. Not only are the elements shaped and arranged to prevent departure of a sheet from the path, and to redirect into the path any sheet tending to depart from the path, but also it will be seen that the elements are so closely spaced each from the next along the path as to minimize any tendencies of the sheets to departure from the path, and thus to permit effective feeding, with minimized chance of jamming, of short pieces of veneer. Such close spacing is practicable because of the low resistance to the flow of the gaseous medium on its way from the tube slot across the veneer sheets and into the rear low pressure chamber afforded by the configuration and arrangement of the elements. Specifically, the jet of gaseous medium issu' ing from the slot 104 of jet tube 99 impinges upon the top of veneer sheet 86 and, having impinged on the sheet, it passes into a gradually increasing space through which it flows in both directions, as indicated by arrows 105 and 106, laterally of the slot and between the curved outer surface 107 of the jet tube and the veneer sheet. Sufficient distance exists between the roller 85 and the tube 99 that the gaseous medium may pass freely therebetween into the space 67 between tiers of jet tubes.

The jet tubes are cylindrical and each includes a jet slot which is of constant size and shape from end to end of the tube. Since the gaseous medium issues from the slot throughout its length, the gas pressure in the tube is gradually diminished from the open end of the tube adjacent the positive pressure chamber 41 to the closed end of the tube adjacent the negative pressure chamber 69. However, the pressure in space 67, 68 outwardly of the tubes is lowest near the negative pressure chamber 69 and highest adjacent wall 43, and, accordingly, the pressure difierential across the slot, between the pressure inside the tube and the pressure outside of the tube, is sufliciently constant to provide jet velocity which is nearly constant throughout the slot length.

Details of the jet tubes are shown in FIG. 7. Tube 108 comprises open end 109 mounted on inturned flange 110 of wall 43 and an opposite end 111 closed by an end wall 112. Wall 112 carries a short threaded shaft or rod 113, which is journalled in support member 114 (corresponding to member 56 described in connection with FIGS. 4 and 5) and locked in desired adjusted position by means of lock nuts 115. Vane or door 116 is arranged to close and selectively to open cleanout opening 117 in end Wall 112.

Slot 118 is seen to extend for substantially the full length of tube 108 and to be interrupted by narrow vertical directing vanes, including vanes 11 9 and 120, which cause the gaseous medium entering the tube as indicated by arrow 12]. to issue from the slot generally as shown by arrows 122, 123, in a direction normal to the axis of the jet tube and toward the veneer sheet 124 and other ma terial being treated. Tube 125, with an upwardly directed slot 126, is similarly arranged.

Referring now to FIG. 8, roller 127 is mounted on shafts 128 and 129 which extend from the ends of the roller and which are journalled in bearing blocks or sleeves 130 and 131, respectively. Means, such as collar 130a, may be provided to prevent the blocks such as block 130 from sliding along shaft 128. Shaft 129 carries sprocket 132 in driven engagement with chain 17. Shaft 128 carries star gear 96 in driving engagement with gear 97, which, in turn, is carried by shaft 133 of the floating roller 134 whereby the rollers rotate together to advance the sheet material 135 being treated. At the drive side, roller 134 includes a shaft 136 journalled in bearing block 137, while shaft 133 at the pressure side is journalled in bearing block 138. Bearing blocks 130, 131, 137 and 138 are identical and interchangeable, but blocks 130 and 131 are mounted to stanchions 31 and 30 at fixed elevation, while blocks 138 and 137 are arranged to float up and down to permit roller 134 to rest upon roller 127 when no material 135 is therebetween and to adjust freely to the thickness of the material 135 and to ride thereon when such material is being fed by the rollers. It will be noted that a vertical clearance slot 139 is provided in the web 140 of stanchion 31 to provide clearance as shaft 133 works up and down. The star gears 96, 97 are of a type to provide efiicient operation with variable spacing between the shafts 128 and 133.

As seen in the top sectional detail view of FIG. 9, each flange of channel member stanchion 31, such as flange 141, carries an inwardly directed vertical guide member, such as member 142, which may be in the form of a half-round rib, and which fits loosely in a respective vertical channel 143 of block 138. The block is thus caged between the flanges of stanchion 31 free to ride up and down. The fit of the block between the guides is sufliciently loose that the block can adjust to any slight departure from precise alignment of the roller, such as may result from slight warping of a stanchion, or from the presence of a veneer sheet near one end and no veneer sheet at the other end of the roller. The guides terminate a short distance above and below the normal block position, and, when gear 97 is removed from shaft 133, the shaft may be raised sufficiently to disengage the block from between its guides, whereupon it may he slipped from the shaft. With block 138 removed suflicient movement of the roller 134- is permitted to free shaft 136 from block 137, whereby it may he removed. Block 130 is removable from shaft 128 when 7 collar 130a and gear 96 are removed, and block 131 is removable when sprocket 132 is detached.

Blocks 130. and 131 are mounted as seen in FIGS. 10, 11 and 12 between the flanges, such as flanges 144, 145 of stanchion 30. A respective knob or stud 146, 147 extend inwardly from each ofthe flanges 144, 145 and supportingly engages in a respective open ended groove 148,

'149 formed in the block 131. The grooves 148 and 149 open at one face 150 of the block, they extend parallel to the bearing axis, or longitudinally of the block, through slightly more than one-half of the length of the block, terminating short of the opposite block face 151, and they are, as shown, diametrically oppositely disposed. The block, as mounted on studs 146 and 147, is free to tilt on the horizontal stud axis which is at right angles to the shaft 129. While the mounting maintains block 131, and block 130 which is similarly mounted, at a fixed elevation, the fit of the studs into the grooves is sufficiently loose to permit the bearing, as with bearings 137, 138, to be self aligning on the respective roller shaft.

The lateral diametrically oppositely disposed channels 152 and 153 which extend at right angles to the bearing axis of block 131, and which correspond to the similar channels, including channel 143, of block 138, permit interchangeability of the bearing blocks. Since blocks 130 and 131 must carry the weight of both rollers, these bearings wear more rapidly than the bearing surfaces of blocks 137, 138 which merely serve as aligning or guide bearings. Since the service requirements of bearings in dryers tend to be severe due to elevated temperatures and often corrosive atmospheres, a substantial saving in bearing cost may be gained by interchanging the bearing blocks used for the driven rollers with those used for the floating rollers after a period of service.

The bearing blocks each comprise a solid cast iron or the like shell or block portion 154 formed to receive caxially a cylindrical sleeve liner 155 pressed therein and which is of bronze or other suitable sleeve bearing material.

Details of the jet tube construction and arrangement are shown in FIGS. 13, 14, and 16, showing portions of tubes 108 and 125 as typical. Tube 108 comprises a sheet metal shell 156 having preferably, a generally cylindrical configuration and importantly having a curved configuration at the under portion 157 adjacent the jet slot 61 which serves to redirect any veneer sheet 124 which may tend to depart from the proper path, which presents no sharp corner or abutment directed toward the veneer path against which any leading edge of a veneer sheet might lodge, which permits economic construction and optimum use of materials, which provides a smooth surface and gradually increasing space for low resistance flow of gaseous medium away from the slot area, and which permits adjustment, by rotation of the tube, of the jet direction into the vertically downward direction seen at 123 in FIG. 13, into the direction inclined against the direction of veneer travel seen at 158 in FIG. 14, or into the direction inclined in the direction of veneer travel seen at 159 in FIG. 15.

The sheet metal shell is formed as by means of a cornice brake to have an upturned, slot-defining flange portion 160 terminating upwardly in an outwardly inclined entrance lip portion 161 adjacent one edge 162 of the sheet and a similar upturned flange portion 163 terminating upwardly in an outwardly inclined entrance lip portion 164 adjacent the other sheet edge 165. The flanges '160 and 163 extend at right angles to a tangent to the underportion 157 of the sleeve at the slot and constitute edge portions of the jet tube member which define its slot.

After the flanges and lips are formed by a brake, with the sheet partially formed as a cylinder, a strip 166 of rectilinearly corrugated metal is applied to flange 160 and is spot welded thereto, preferably at each alternating fiat 167, 168, the welds being indicated by broken lines at 169, 170. Thesheet is now formed into the complete cylinder by bringing flanges 160, 163 toward each other until the intervening alternate flats of the corrugation 171, 172 meet flange 163, whereupon bead welds, such as welds 173, 174, are run along the lower edge 175 of the corrugated strip joining it to the metal sheet adjacent the opening of the slot. It has been found that a bead weld at about every fourth or fifth corrugation is sufiicient.

The laterally extending portions 119, which extend laterally across the slot and which join the aforementioned flats each to the next comprise vertical directing batfles for the gaseous medium passing through and issuing from the jet slot between the flanges and 163 and further serve to maintain the slot dimensions fixed and constant.

In typical operation, the dryer may comprise 5 sections arranged into a two-section green end zone, followed by a two section dry end zone, and with a final section or cooling zone open to the atmosphere at its drive or negative pressure side. If desired, one section of the dryer as shown herein could be operated as a cooling zone by merely opening the housing doors on the negative pressure side, by omitting or turning off any heating means, and by taking in fresh outside air to the fan whereby the fan would force fresh air into the jet tubes and the air, after impinging upon the veneer, would merely exhaust to the atmosphere rather than being recirculated. The drying zones of the machine may be operated at a temperature of the gaseous medium in the pressure chamber of about 300 to 350 degrees F. The flow from each jet slot may be at a velocity of 2500 feet per minute. For a four to six section dryer operating under these conditions, a veneer sheet may complete its passage through the dryer in 8 or 10 minutes, more or less, depending upon thickness, density, moisture removal requirements and other conditions.

While only certain preferred embodiments of this in vention have been shown and described by way of illustration, many modifications will occur to those skilled in the art and it is, therefore, desired that it be understood that it is intended in the appended claims to cover all such modifications as fall within the true spirit and scope of this invention.

What is claimed as new and what it is desired to secure by Letters Patent of the United States is:

1. In a dryer for wood veneer sheets including a drying section and means for advancing veneer sheets to be dried through the section from a forward to a rearward end thereof along a predetermined path, two hollow elongated conduit members of constant cross-section from end to end, each of said members having two longitudinal edge portions defining therebetween a respective elongated side slot extending substantially from end to end of said member, each said member extending laterally of said path and being oriented to direct its said slot toward said path, one said member being disposed on one side of said path and the other said member being spaced therefrom and disposed on the other side of said path, means for feeding said veneer sheets generally along said path and through the space between said members, said means comprising two pairs of feed rolls, each pair including an upper and a lower roll and said pairs being disposed adjacent said conduit members with one pair forwardly thereof and the other rearwardly thereof, each said conduit member presenting toward veneer sheets advancing in said path from said one pair of feed rolls a surface curving away from the center of said path progressively with distance from said slot and positioned to intercept those errant misaligned veneer sheets which tend to depart from the path as they are being fed theretoward and to re-direct such intercepted errant sheets into the space between said members and thence in a direction between the rolls of the other pair, and means for introducing heated gaseous medium into said conduit members to escape through said slots toward the veneer sheets as they pass along said path.

2. In a sheet material dryer, a series of sections of conveyor feed roll and jet tube assemblies, means to supply heated gaseous medium into the jet tubes of said sections, each section comprising a plurality of upright side frame elements connected only at top and bottom to respective upper and lower horizontal side frame members which terminate at each end of the section, rigid foundation means underlying said lower side frame members, each section being joined to the next through slip connections between the said horizontal side frame members of the respective sections, the feed rolls and jet tubes in each section being supportedly mounted on said upright side frame elements only and being positioned between said upper and lower frame members, said feed rolls being arranged to provide a straight horizontal path for the sheet material extending through said plurality of sections between the jet tubes thereof, whereby longitudinal expansion and contraction of said side frame members due to heating and cooling is absorbed in said slip connections. 3. A sheet material dryer comprising a rigid foundation including side edge portions, an assembly comprising a plurality of conveyor feed rolls and jet tubes and including a plurality of upright side frame elements footing on said foundation spaced inwardly of said side edge portions, said assembly further comprising means supportingly mounting said conveyor feed rolls and jet tubes on said frame elements, an outer housing spaced outwardly of said assembly supported on said side edge portions of said foundation whereby alignment of said assembly is independent of expansion and contraction of said housing, and heating and recirculating means located in the space-between said assembly and housing for supplying heated gaseous medium into said tubes and for collecting and heating such medium following ejection from said tubes. 4. A sheet material dryer comprising a plurality of assembled conveyor and gas impacting equipment sections serially arranged between a feed end and a delivery end of the dryer, a housing extending between said ends and enclosing said sections, each section comprising an apertured partition along one side, a plurality of feed rolls, bearings for said feed rolls at each side provided with a plurality of apertures therethrough, a plurality of jet tubes having open ends aligned with said apertures, and means for mounting the jet tubes disposed at each side of the section, said tubes having elongated slots extending longitudinally thereof from adjacent said partition to adjacent the other side of the section and having closed ends adjacent said other side of the section, said other sides of each of said sections being generally open, means in said housing for circulating gaseous medium from said open side of each section across the top of the section and into said tubes through the apertures in said partition and thence for ejection from said slots and subsequent passage out of the section through the said other side thereof, said means including means for adding heat to said medium during the passage thereof in said housing exteriorly of the section, a foundation underlying said sections and housing, means supportedly mounting said sections on said foundation supporting the whole weight thereof and separate means supportingly mounting said housing on said foundation, and means permitting relative movement connecting the feed end of the first said section to the adjacent end of the housing and other means permitting relative movement connecting the delivery end of the last said section to the adjacent end of said housing whereby thermal expansions and contractions of said housing and sections do not transmit misaligning forces from the housing to the sections.

5. In a sheet material dryer, an upright plate member having a round aperture therein and having an outer face and an inner face, a circular flange around said aperture extending from said inner face, an elongated jet tube having a circular open inlet end fittingly engaged on said flange, said tube extending from said inner face and terminating spacedly therefrom in a closed end, support means for said closed end of said tube comprising an upright post and means connecting said closed end to said post, means for mounting said post and said plate memher on a foundation, said tube being provided between its ends with a lateral jet opening, means including said outer face of said plate member defining a pressure chamber, and means for supplying heated gaseous medium into said chamber for passage through said aperture into said tube.

6. The combination according to claim 5 wherein said means connecting said closed end of said tube to said post comprises journal means rotatably connecting the tube and post and axially aligned with said flange whereby said tube is selectively rotatably positionable about said axis to adjust the position of its said jet opening.

References Cited UNITED STATES PATENTS 1,725,708 8/1929 Fowler 34-205 X 2,323,918 7/1943 Kiernan 34-23 X 2,370,811 3/1945 Osgood 34-23 X 2,386,286 10/1945 Beckley 34205 FREDERICK L. MATTESON, JR., Primary Examiner. C. R. REMKE, Assistant Examiner. 

1. IN A DRYER FOR WOOD VENEER SHEETS INCLUDING A DRYING SECTION AND MEANS FOR ADVANCING VENEER SHEETS TO BE DRIED THROUGH THE SECTION FROM A FORWARD TO A REARWARD END THEREOF ALONG A PREDETERMINED PATH, TWO HOLLOW ELONGATED CONDUIT MEMBERS OF CONSTANT CROSS-SECTION FROM END TO END, EACH OF SAID MEMBERS HAVING TWO LONGITUDINAL EDGE PORTIONS DEFINING THEREBETWEEN A RESPECTIVE ELONGATED SIDE SLOT EXTENDING SUBSTANTIALLY FROM END TO END OF SAID MEMBER, EACH SAID MEMBER EXTENDING LATERALLY OF SAID PATH AND BEING ORIGENTED TO DIRECT ITS SAID SLOT TOWARD SAID PATH, ONE SAID MEMBER BEING DISPOSED ON ONE SIDE OF SAID PATH AND THE OTHER SAID MEMBER BEING SPACED THEREFROM AND DISPOSED ON THE OTHER SIDE OF SAID PATH, MEANS FOR FEEDING SAID VENEER SHEETS GENERALLY ALONG SAID PATH AND THROUGH THE SPACE BETWEEN SAID MEMBERS, SAID MEANS COMPRISING TWO PAIRS OF FEED ROLLS, EACH PAIR INCLUDING AN UPPER AND A LOWER ROLL AND SAID PAIRS BEING DISPOSED ADJACENT SAID CONDUIT MEMBERS WITH ONE PAIR FORWARDLY THEREOF AND THE OTHER REARWARDLY THEREOF, EACH SAID CONDUIT MEMBER PRESENTING TOWARD VENEER SHEETS ADVANCING IN SAID PATH FROM SAID ONE PAIR OF FEED ROLLS A SURFACE CURVING AWAY FROM THE CENTER OF SAID PATH PROGRESSIVELY WITH DISTANCE FROM SAID SLOT AND POSITIONED TO INTERCEPT THOSE ERRANT MISALIGNED VENEER SHEETS WHICH TEND TO DEPART FROM THE PATH AS THEY ARE BEING FED THERETOWARD AND TO RE-DIRECT SUCH INTERCEPTED ERRANT SHEETS INTO THE SPACE BETWEEN SAID MEMBERS AND THENCE IN A DIRECTION BETWEEN THE ROLLS OF THE OTHER PAIR, AND MEANS FOR INTRODUCING HEATED GASEOUS MEDIUM INTO SAID CONDUIT MEMBERS TO ESCAPE THROUGH SAID SLOTS TOWARD THE VENEER SHEETS AS THEY PASS ALONG SAID PATH. 